Hydrofluoroolefins (HFOs), as compared with chlorofluorocarbons (CFCs), Hydrochloroflurocarbons (HCFCs) and hydrofluorocarbons (HFCs), do not contain chlorine and do not pose a threat to the Earth's ozone layer, meanwhile have low Global Warming Potential, which have now become the focus of research in F-chemical industries. 1,3,3,3-tetrafluoropropene, i.e., HFO-1234ze, as one of hydrofluoroolefins, has an ozone depletion potential of 0, has a Global Warming Potential of 6, and can be used as refrigerants, foaming agents, aerosol propellants, extinguishing agents, heat-transfer media, propellants, gaseous dielectrics, sterilizing agent carriers, monomers of polymers and intermediates of medicine and pesticide, and it is widely used in the fields of chemical industry, fire-fighting, aerospace and aviation.
At present, four methods have mainly reported for preparation of HFO-1234ze including fluorine-chlorine exchange, dehydrohalogenation, telomerization and carbene reaction.
There are most reports on the fluorine-chlorine exchange. JP10007604, U.S. Pat. No. 6,472,573 and EP486333 report a method for synthesizing HFO-1234ze by one-step gas phase fluorination with 1-chloro-3,3,3-trifluoropropene (HCFC-1233zd) as raw material, however, the reaction material HCFC-1233zd of the method is expensive and difficult to obtain, furthermore, the transport of the raw material is also inconvenient; the catalysts are chromium-containing catalysts, these chromium-containing compounds and catalyst will cause damage to the human digestive tract and kidney, especially the high-valence chromium has a strong carcinogenic effect, and is unfriendly to people and the environment in the processes of production and use, and will cause serious harm; CN200810000765.X reports a method for preparing HFO-1234ze by gas phase fluorination with 1,1,1,3,3-pentachloropropane (HCC-240fa) as raw material, however, the selectivity of the HFO-1234ze in the method is low, and is only about 50%. US2006030744 reports a method for synthesizing HFO-1234ze using 3,3,3-trifluoropropene (HFO-1243) as raw material, however, the raw material of the method is expensive, the route is complicated, and the addition reaction process is difficult to control.
With respect to dehydrohalogenation, U.S. Pat. No. 7,592,494, EP2014637, EP0974571, Chinese Patent No. CN101265155, Chinese Patent No. CN101466656 and Japanese Patent No. JP10007605 respectively report a method for synthesizing HFO-1234ze using 1,1,1,3,3-pentafluoropropane (HFC-245fa) as raw material, however, the reaction raw material HFC-245fa is expensive. U.S. Patent No. US20090278075 reports a method for preparing HFO-1234ze and HFO-1234yf with 1,1,1,2,3-pentafluoropropane (HFC-245eb) as raw material, however, the selectivity of the HFO-1234ze in the method is low.
With respect to telomerization, US20050245773 and US20050245774 report that HFO-1234ze is obtained by continuous fluorination after telomerization with halogenated methane and halogenated ethylene as raw materials, however, the route of such a synthesis method is complicated, the catalyst is expensive and easy to coking and deactivation, both the raw material conversion and the selectively of target product are low.
With respect to the process for the preparation of carbene reaction, US20050245774 reports that HFO-1234ze is produced by high temperature reaction of difluorocarbene and vinylidene fluoride monomers in the same reactor at a temperature of above the cracking temperature of the difluorocarbene precursor, the reaction temperature of the synthesis method is high, the yield is low, and the reaction condition is harsh, and there is no industrial application value.
Although there are many methods disclosed presently for preparing HFO-1234ze, they have the deficiencies such as: the raw materials are expensive and difficult to obtain, the catalyst is unfriendly to the environment, and the reaction condition is harsh and the like. Thus, there is a need of a continuous improvement and more efficient preparation methods.